implement glusterfs volume plugin

Signed-off-by: Huamin Chen <hchen@redhat.com>

examples_test.go

@@ -181,6 +181,9 @@ func TestExampleObjectSchemas(t *testing.T) {
 		"../examples/iscsi/v1beta3": {
 			"iscsi": &api.Pod{},
 		},
+		"../examples/glusterfs/v1beta3": {
+			"glusterfs": &api.Pod{},
+		},
 	}
 
 	for path, expected := range cases {

glusterfs/README.md

@@ -0,0 +1,47 @@
+## Glusterfs
+
+[Glusterfs](http://www.gluster.org) is an open source scale-out filesystem. These examples provide information about how to allow containers use Glusterfs volumes.
+
+The example assumes that the Glusterfs client package is installed on all nodes.
+
+### Prerequisites
+
+Install Glusterfs client package on the Kubernetes hosts.
+
+### Create a POD
+
+The following *volume* spec illustrates a sample configuration.
+
+```js
+{
+     "name": "glusterfsvol",
+     "glusterfs": {
+        "endpoints": "glusterfs-cluster",
+        "path": "kube_vol",
+        "readOnly": true
+    }
+}
+```
+
+The parameters are explained as the followings. 
+
+- **endpoints** is endpoints name that represents a Gluster cluster configuration. *kubelet* is optimized to avoid mount storm, it will randomly pick one from the endpoints to mount. If this host is unresponsive, the next Gluster host in the endpoints is automatically selected. 
+- **path** is the Glusterfs volume name. 
+- **readOnly** is the boolean that sets the mountpoint readOnly or readWrite. 
+
+Detailed POD and Gluster cluster endpoints examples can be found at [v1beta3/](v1beta3/) and [endpoints/](endpoints/)
+
+```shell
+# create gluster cluster endpoints
+$ kubectl create -f examples/glusterfs/endpoints/glusterfs-endpoints.json
+# create a container using gluster volume
+$ kubectl create -f examples/glusterfs/v1beta3/glusterfs.json
+```
+Once that's up you can list the pods and endpoint in the cluster, to verify that the master is running:
+
+```shell
+$ kubectl get endpoints
+$ kubectl get pods
+```
+
+If you ssh to that machine, you can run `docker ps` to see the actual pod and `mount` to see if the Glusterfs volume is mounted.

glusterfs/endpoints/glusterfs-endpoints.json

@@ -0,0 +1,13 @@
+{
+    "apiVersion": "v1beta1",
+    "id": "glusterfs-cluster",
+    "kind": "Endpoints",
+    "metadata": {
+        "name": "glusterfs-cluster"
+    },
+    "Endpoints": [
+        "10.16.154.81:0",
+        "10.16.154.82:0",
+        "10.16.154.83:0"
+    ]
+}

glusterfs/v1beta3/glusterfs.json

@@ -0,0 +1,32 @@
+{
+    "apiVersion": "v1beta3",
+    "id": "glusterfs",
+    "kind": "Pod",
+    "metadata": {
+        "name": "glusterfs"
+    },
+    "spec": {
+        "containers": [
+            {
+                "name": "glusterfs",
+                "image": "kubernetes/pause",
+                "volumeMounts": [
+                    {
+                        "mountPath": "/mnt/glusterfs",
+                        "name": "glusterfsvol"
+                    }
+                ]
+            }
+        ],
+        "volumes": [
+            {
+                "name": "glusterfsvol",
+                "glusterfs": {
+                    "endpoints": "glusterfs-cluster",
+                    "path": "kube_vol",
+                    "readOnly": true
+                }
+            }
+        ]
+    }
+}